There is a long history of light fixtures that have an adjustable color output. For instance, there are theater light fixtures that include a bright, white incandescent bulb, with replaceable colored gels or filters that can be cycled into and out of the beam as desired. Although commonly used, these fixtures commonly produce a great deal of heat, and use a significant amount of electrical power to power the incandescent bulb. In addition, the bulbs need periodic replacement.
It would be advantageous to have a tunable light fixture that uses one or more light emitting diodes (LEDs) as its light source. Compared with a conventional incandescent-based fixture, an LED-based system could be smaller, could use less power, and may require less maintenance.